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Re: DF-2 switching conundrum: the flip-flop flaps

7/11/2000 9:20 PM
John Greene
Re: DF-2 switching conundrum: the flip-flop flaps
"(*Much to my surprise, the DF-2 is actually an octave *divider*. "What!?" you say. How could it be an octave divider if it produces overtones? Curious thing, that. The VCO syncs to the fundamental being fed in, but it outputs a much higher tone. That tone, in turn, goes through a 4013 flip-flop and gets divided in 2 then in 4, JUST LIKE a Bluebox or any other run of the mill octave down effect. These "octave and two below" tones are then mixed in your desired proportion, and blended in with the regular fuzz when you hold down the pedal. If one could figure out a way to output a lower frequency from the on-board VCO, then your DF-2 "feedback" tones could actually be a surly growl that fades in when you hold down the pedal. Neat!!)  
I don't see that. I see the 'Fundamental Detector' driving the 'Set' and 'Reset' controls of the one flip-flop which does nothing more that square-up the fundamental. This is fed into one input of the phase-comparator. The VCO is driving the clock of a second flip-flop which is a divide-by-2. The output of the divide-by-2 is fed into the second input of the phase comparator so the VCO must be running at twice the fundamental. These are the two signals that are mixed together.  
I don't see another divider. So I would say it produces the fundamental and a one octave up.  
7/12/2000 1:24 PM
Mark Hammer

Ah, well. This is what comes from being a self-taught putterer, rather than a formally trained EE type. Parts of the schematic looked so familiar, but PLL's are still a mystery to me.  
On the other hand, could it conceivably be possible to *add on* an additional flip-flop to produce the octave growl/drone I suggested? The DF-2's ability to hold a selected tone while you play over it makes the notion of a drone-tone very intriguing.
7/12/2000 3:32 PM
John Greene

"On the other hand, could it conceivably be possible to *add on* an additional flip-flop to produce the octave growl/drone I suggested? "
If you change the second input of the phase comparator to be the output of the VCO instead of the output of the flipflop (and probably change a capacitor value) you would get an octave down effect. Then, by adding another flip-flop you could get a 2-octave down tone. Add another and get a 3-octave down tone, etc.  
7/29/2000 3:21 PM
Help with DF-2!
I have this unit too.  
I like the Feedbacker mode option, but distortion  
on this unit i donīt like.  
Are there better distortions, and I want  
to add switch for BYPASS DISTORTION and using  
only FEEDBACKER effect.  
Is it possible?  
I have this zipped schematic, so where are  
this two points, where can I insert switch?  
Is this possible?  
As i hear(maybe Iīm mistaked) the FEEDBACKER curcuit is BEFORE the Distortion, because color and  
thickness of generated overtone is depended on  
amount of DISTORTION and color of Tone.  
Or how to INCREASE output volume of this unit?  
I like a RAT pedal, or Boss TURBO DISTORTION ,.beacause these units have  
really STRONG output.  
Please, help  
7/31/2000 12:52 AM
Mark Hammer How to unfuzz your DF-2
The simplest thing is to lift the ground connection of diodes D2 and D3. These are the diodes that do the clipping. Disable them and you will have a feedbacker that performs the feedback function but has no fuzz. All the other controls will work as before, except that the "distortion" control will simply act as a gain booster.  
The DF-2 splits the signal at Q1. The straight signal goes directly to the initial booster stage of the clipping circuit, where it joins up with the output of the much more complex feedbacker circuitry. Both original and overtone signals then go through the clipping, tone control, and level-setting circuitry. So, distortion applies to everything that comes out of the DF-2.  
If you cancel the clipping diodes, you will also get a volume boost, because the clipping diodes normally limit the output level. The remaining components in that region - R22 and C11 - form a lowpass filter with a turnover frequency of just over 7200hz. You *could* remove the capacitor to give an even "cleaner" sound, but this frequency range strikes me as higher than most guitar speakers can easily reproduce, so I don't see the extra treble as necessary.
7/31/2000 7:37 PM

I maked this thing with diodes.  
I removed diodes, then removed PCB off, maked a hole on backside(by DC jack), and added mini 3 position toggle switch.  
1. position- original diodes  
2. position- off diodes-boost, bigger volume,  
very good sound  
3. position-I added 2x 3mm red led...  
GREAT SOUND!!!!!!!! a bit like Marshall GUVNOR or TURBO RAT ,now is it my FAVORITE PEDAL.  
One more time THANK YOU , MARK  
7/31/2000 8:41 PM
Mark Hammer

You are very welcome. Thank you for being brave enough to try it. I will have to try it on my own.  
I am curious about how it sounds when the feedbacker is combined with a clean boost.

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